The invention relates to a machine for processing workpieces on which a sequence of different processing steps is to be carried out, especially a machine for processing workpieces of thermally deformable material such as hollow glass objects. Here, it is not necessary that a thermal softening need precede each processing step.
The invention relates further to individual processing units for such a machine and, in special application, a processing unit for, on the one hand, the edge melt-off and the forming of spouts on glass vessels and, on the other hand, also a processing unit for printing onto such vessels with screen printing.
In known manufacturing lines for hollow glass objects, the individual work steps are generally carried out on rotation units of which each is equipped with a plurality of workstations of the same kind. The workpieces are supplied to such a rotation unit sequentially at a specific location by means of complex handling systems, which often require a multiple transfer of the workpiece, and are again removed after processing via additional handling units at another location. It was up to now conventional to carry out the melt-off of the work ring from hollow glass vessels and the subsequent forming of a spout thereon during series manufacture on separate rotation units. Disturbances in the flow of the articles arise because of the multiple handling operations. Furthermore, often article-specific tools are required for the handling apparatus. In the rotation unit, all stations have to be equipped with tools even when the required machine capacity can be provided with fewer stations, for example, with small quantities. This not only leads to increased investment costs for the tools but also to unnecessarily high standstill times when the articles are exchanged. If a disturbance occurs on a rotation unit or on a handling unit, then, as a rule, the entire machine or assembly line must be shut down.
In the following, the machine of the invention is described with respect to the application to hollow glass objects and is primarily for use in a continuous assembly line manufacture. In its basic configuration, the machine according to the invention can, however, also be applied to processing workpieces made of other material and, in a special configuration of the workstations, the machine can also be utilized for carrying out processing steps which are not mentioned in the context of this description. For this reason, the description in its application to glass objects should not be understood as limiting.
The object of the invention is a machine for processing workpieces in a continuous assembly line which permits a flexible mode of work and can function with a minimum of work tools and which reduces the handling operations and does not have to be switched off when there is a disturbance at a single processing unit.
The machine of the invention is for processing workpieces of a deformable material including hollow glass objects. The machine includes: at least two processing units for the workpieces and each processing unit having at least one workstation; a conveyor unit for supplying the processing units with the workpieces to be processed and for taking processed workpieces away from the processing units; the conveyor unit being configured to move the workpieces in a basic direction; the two processing units being of the same kind and being arranged along the conveyor unit; the one workstation of each processing units being arranged stationary; each processing unit including two handling units and each of the handling units functioning to take a workpiece from the conveyor unit, move the workpiece to and in the workstation and return the processed workpiece back to the conveyor unit; and, the handling units being configured for a time-displaced, like function simultaneous work sequence in a direction which runs essentially transversely to the basic direction of the conveyor unit.
When, for a conventional machine, individual processing units configured as rotation units were arranged one behind the other with each processing unit carrying a plurality of the same workstations, the invention provides a plurality of the same processing units arranged along the assembly line one behind the other, the processing units being equipped only with a low number of stationary, especially different, workstations so that some work operations can be carried out sequentially on the workpiece, the workpiece being held by one and the same workpiece holder without further transfer while passing through a processing unit.
When it is required that the conveyor unit be configured to move the workpieces in a basic direction which, in general, is the production direction of the assembly line, this does not mean that the conveyor unit must necessarily be a linear conveyor. In accordance with space conditions, the conveyor unit can have angles and turns insofar that the individual processing units are arranged in a series one behind the other next to the conveyor unit and the workpieces, when they leave a processing unit, are moved farther in the same direction from which they had come. Preferably, the conveyor unit is, however, a linear conveyor and especially preferred is such a conveyor having two parallel paths. On a loading conveyor, the workpieces are moved ahead and, on a parallel unloading conveyor, are moved farther. Of course, the unloading conveyor of a machine can simultaneously be the loading conveyor for the next-following machine.
The machine is so configured that the loading conveyor as well as the unloading conveyor are clock driven so that the workpieces can be removed from the conveyor unit at standstill thereof and can again be unloaded thereon. When the workstations of the processing units are characterized as stationary, this does not preclude that parts of a workstation can also be movable to a limited extent. Rather, the characterization of stationary expresses that the workstations are configured in total as stationary and do not move as on the rotation unit.
The two handling units, which belong to each processing unit, move the workpieces essentially transversely to the conveyor unit. Transverse must not necessarily mean at right angles. Depending upon the space requirements or space use, the processing units can be aligned at a specific angle to the basic direction of the conveyor unit.
The processing units are practically configured to be modular-like so that, if required, a processing unit can be exchanged without difficulty for one of the same kind. The number of processing units of the same type, which are arranged one behind the other, is dependent upon the type and duration of the working steps to be carried out in such a processing unit when a certain production assembly line capacity is pregiven. All processing units of a type, which are in service, operate more or less in parallel, that is, when the clocked conveyor unit stops, workpieces are simultaneously taken from the conveyor unit by all like processing units or are again supplied thereto. This can be achieved via a controlled interaction between the conveyor unit and the processing units. If one of the processing units becomes defective, then it can easily be taken out of the sequence. The conveyor unit is then loaded with workpieces in a different way. Purposefully, one or two processing units are provided as reserve and can be taken into service when others are temporarily out of service. Also, the capacity of the machine can be adapted to different production sequences in that one selectively switches some processing units out of the sequence in a controlled manner and, for example, for small lots or longer operating times in other machines of the assembly line, the particular machine is operated only with a reduced number of operating units of the same type.
Further features of the invention which affect only the processing unit are described in the following with respect to the individual processing units.
The individual processing unit is provided with two essentially the same handling units each of which is equipped with a single workpiece holder for an individual workpiece. The workpiece remains connected to the workpiece holder during the entire sequence in the processing unit from the pickup from a close conveyor unit until delivery to the conveyor unit. A delivery of a workpiece to another unit does not take place. The two handling units are so configured that they run through functionally the same work cycles but are displaced in time. The individual processing unit can be provided with only one workstation but, preferably, is provided with two or fewer workstations. The complete functionality of the invention becomes effective only when these workstations are of a different type, that is, a series of sequential work steps can be carried out with them on one workpiece. Precisely this mode of operation requires the time-displaced interaction of the two handling units with the different workstations.
In a preferred embodiment, the workstations of a processing unit are arranged in a series in a such a manner that one can define a vertical central plane which runs through the centers of the workstations. This central plane extends, as indicated above in another way, purposefully approximately transverse or even exactly at right angles to the basic direction of the conveyor unit to which the processing unit is connected. The two handling units are preferably arranged on both sides of this central plane and each has a primary carriage with which the handling units can be moved horizontally and parallelly in fixed guides at both sides of the central plane.
Corresponding to the arrangement of the workstations with their imaginary center points in the central plane, the imaginary center points of the workpiece holders also lie, in general, in the central plane and are also only movable in this central plane in the preferred embodiment. The horizontal displacement in the X direction takes place via the primary carriage. In addition, the workpiece holders are held on projecting arms from the respective sides into the central plane and are also movable in elevation. This second displacement possibility in the Z direction can be realized via a secondary carriage which is driven perpendicularly on the primary carriage. The possibility is also present to configure the workpiece holders to be pivotable on the respective arm in the central plane which is practical when the workpiece, as a consequence of the working steps, has to be transferrable from an upright into a rotated position or even into an inclined position in the vertical plane. The movement possibilities of the workpiece holders in the X and Y directions can, in the same manner, also be carried out in that a primary carriage is movable in elevation on the machine frame and a secondary carriage is movable horizontally on this frame. What is essential here is that a movability of the workpiece holders is possible in all directions of the central plane.
The vertical movability of the workpiece holders serves not only to guide the workpiece, for example, to a workstation, which is located below, and to lift the same therefrom, but is also necessary in order to prevent collisions between the workpiece holders and the workpieces carried thereby when the two handling units are to pass each other in opposite directions. In this situation, one of the workpiece holders can be lifted such that the other workpiece holder can be moved along under the first workpiece holder and the workpiece carried thereby in the central plane.
For various work steps, it is necessary that the workpiece be rotated during processing. For this case, the workpiece holders are provided with rotational drives. In a special configuration, these rotational drives can be so configured that they can be adjusted at precise angular positions. This is, for example, practical when a work step is to be carried out on a specific peripheral location of the workpiece and this peripheral position can be automatically driven to. To hold the workpiece, the workpiece holders include suction cups, chucks or other known aids. Thus, for example, glass vessels are to be held at the base thereof for processing the edge thereof. For this purpose, suction cups are used in a manner known per se.
It is purposeful to arrange all workstations at approximately the same elevation below the handling units for processing steps which can be carried out exclusively on a suspended workpiece, that is, on a workpiece held from above. In an embodiment of this kind, a simplified configuration results in that one provides for horizontal guidance for the two handling units on both sides of a single fixed cross-beam which extends at a sufficient elevation above the workstations. If, in contrast, workstations are required to whose work tools the work must be approached from below, space is needed between the handling units so that these handling units are guided on separate lateral frame parts.
A special aspect of the invention lies in the application for melting off the work ring, the melting of the separating edge and the forming of a spout in the edge of a glass vessel. The ring melt-off and the forming of the spout was conventionally carried out in two different processing units. In contrast, the processing unit of the invention has, in series, a first workstation for melting off and removing the work ring of a glass vessel as well as for fusing the cut-off edge, a further workstation for preheating the region for the spout and a third workstation for forming the spout. This processing unit will be explained in greater detail in the context of the description of an embodiment.
The joining of the two above-mentioned work steps in one processing unit affords, inter alia, the advantage that the glass vessel must not be heated again all the way from a lower temperature for forming the spout, at least at this location. The glass vessel is transferred into the second workstation as long as its edge is still warm from melting off the work ring. In this way, a considerable amount of energy is saved. Furthermore, separate drives for the moving sequences of work tools become substantially unnecessary because, with the numerically controlled handling unit, the workpiece can be moved in the desired manner relative to the work tool. The handling unit can carry out movements in all three spatial directions while including the rotatability of the workpiece holder. This applies, for example, for warming the edge region for the spout. A desired edge region can be warmed at the desired intensity while using a single stationary burner by means of a rotational angle movement back and forth and a superposed translatory movement of the workpiece toward the burner and away from the burner. Also, the forming of the spout can take place via a movement of the workpiece toward the work tool.
Finally, two workpieces can always be processed simultaneously in the processing unit because of the time-displaced movement sequence of the two handling units.
A further application of the claimed machine, which is provided in accordance with the invention, and of the claimed operating units is the printing of rotationally-symmetrical objects with print formats in the silk screen printing process.
The printing of rotational-symmetrical objects in the silk screen printing process usually takes place with a horizontally arranged silk screen frame which rolls off on the object rotated about its horizontally aligned axis (at least insofar as the printing of cylindrical surfaces is concerned). When the object, which is to be printed (for example, a hollow glass vessel which is brought on a loading belt to the processing unit with its opening directed downwardly), is grasped from above at its base by a workpiece holder configured as a suction cup, then it is necessary for carrying out the printing process that the workpiece holder with the workpiece carried thereby be pivotable into a horizontal direction of its axis. The workpiece holders of the two handling units are therefore, in the present application, attached by means of a cropped angular arm on the horizontally movable primary carriage of the handling units. One arm of the angular level can be pivoted about a horizontal axis on the primary carriage.
The processing unit for the silk screen printing can have two workstations, namely, one for adjusting the fit and the other for the actual printing process. For glass vessels having a spout, the printing, in general, should be applied at a specific peripheral position relative to the spout so that the object, which is to be printed, has to be aligned in a specific angular position before its introduction into the actual printing station. This takes place in the registration station. The work sequence is purposefully so configured that one of the workpiece holders takes over an object from the loading belt in a perpendicular position and transfers the same also in this position to the registration station while another object is located in horizontal alignment in the printing station. In this horizontal alignment, and after the end of the printing process, the second tool holder with the printed object can pass over the first workpiece holder in order to drop off the printed workpiece on the discharge belt while the first workpiece holder with the aligned object now pivots into the horizontal position in order to move into the printing station.
In a special embodiment of the printing station, this station can have more than one silk screen frame one behind the other or a subdivided silk screen frame viewed in the direction of movement of the primary carriage of the handling unit so that a second printing on the workpiece can be carried out after an additional horizontal movement thereof. Here, it can be a second picture but also a second color of a multicolor image. In order to guarantee a problem-free rotation of the workpiece to be printed beneath the silk screen frame, it can be practical to drive the object, which is to be printed, with its opening, which faces away from the suction cup, toward a centering spindle which supports the other end of the object during rotation.
Often, the peripheral surfaces of a rotational-symmetrical object, which is to be printed, are not cylindrical but conical. It is necessary to incline the rotational axis of the object in order to bring this object, which is to be printed, horizontally under the silk screen frame with a surface line of its conical region. In a special embodiment of the invention, this is possible via a corresponding pivoting of the rotatable workpiece holder. The above-mentioned spindle for rotation stabilization can also be provided in this case if it is configured to be correspondingly pivotable. The silk screen printing on a conical surface requires a special circular path shaped sequence movement of the silk screen frame. A silk screen printing arrangement which makes this possible in the smallest space is described in German patent publication 199 21 306. Such an arrangement can be used in the context of the present invention.